The only parts I would cut are the ones that are dead, broken or disfigured.

Cutting living plant material is throwing away stored food material.

Plus, the tree is now under the stress healing the open wounds created by the cuts.

Plant, wait, trim branches that have died. The tree knows what it should abandon or not.

For the most part, that IS outdated info. The only time it may be appropriate is if a very young fruit tree that is little more than a whip or a single vertical shoot with no side branching. Cutting back the leader by a third or so will encourage side branching and since the tree is (or should be) dormant, the transpiration issue or foliage to root mass issue is null and void. Not at all the same as when transplanting or planting a more mature and no longer dormant subject.

This rough rule of thumb also tends to be most relevant to fruit trees or something like the Arbor Day trees that are really just seedlings or only first or second year grafts.

The tree is an Amelanchier 'Autumn Brilliance' clump form, something of a cross between a tree and a shrub. Instructions for shrubs are pretty clear to "thin 1/3 to 1/2 shrub by removing large branches" and topping others to improve shape. For trees to remove any broken or damaged branches/roots and some shaping pruning.

I'm going to consider it a tree and do very little pruning.

Thanks Bill and Gardengal.